High speed firing mechanism

ABSTRACT

A HIGH SPEED ACTUATOR OPERABLE IN RESPONSE TO GENERATED GASES INCLUDING AN ACTUATOR PIN, A PRESSURE RESPONSIVE SURFACE AND A PRESSURE RESPONSIVE CHAMBER WHEREBY GAS PRESSURE AGAINST THE PRESSURE RESPONSIVE SURFACE CREATES A BACKWARD THRUST AND GAS PRESSURE BUILDUP WITHIN THE CHAMBER CREATES A FORWARD THRUST.

Sept. 28, 1971 cs. s. JACKSON HIGH SPEED FIRING MECHANISM Filed Dec. 31, 1968 INVENTOR GILBERT S. JACKSON United States Patent 3,608,425 HIGH SPEED FIRING MECHANISM Gilbert S. Jackson, West Hyattsville, Md., assignor to Jesse D. Steele, Chevy Chase, Violet Ann Ash, Rockville, and Nicholas J. Aquilino, Crofton, Md., fractional part interest to each Filed Dec. 31, 1968, Ser. No. 788,223 Int. Cl. F41d 11/16 US. Cl. 89=--27 Claims ABSTRACT OF THE DISCLOSURE A high speed actuator operable in response to generated gases including an actuator pin, a pressure responsive surface and a pressure responsive chamber whereby gas pressure against the pressure responsive surface creates a backward thrust and gas pressure buildup within the chamber creates a forward thrust.

BACKGROUND OF THE INVENTION The present invention relates to linear actuators, and more particularly, to a linear actuator having a high speed repetition rate suitable for use as a firing mechanism in a rapid fire weapon.

Modern technology is presently developing rapid fire weaponry systems such as high speed ballistic launchers and automatic weapons. A primary shortcoming of such systems has been the inability of firing mechanisms to operate satisfactorily at the required high speeds, by way of example, up to a thousand rounds per second. Attempts have been made using gas operated mechanism in combination with mechanical spring assistors but all have been found to be unreliable for sustained high speed operation. Electronic actuators for regulating firing pin rates operate satisfactorily but require expensive and bulky equipment.

SUMMARY OF THE INVENTION The present invention is directed to a high speed linear actuator of a type suitable for use as a firing pin in automatic weapons or ballistic missile launchers'which overcomes the disadvantages of the prior art firing pin mechanisms and provides cleaner operation, less fouling, greater effective work life, elimination of high speed spring float, and mechanical lever or fulcrum action. The actuator includes a firing pin element, a pressure responsive surface movable in response to generated gas pressure to move the actuator to a loaded or retracted position and a pressure chamber exposed to generated gases so as to expand and create a forward thrust to move the actuator to the firing position.

Among the objects of the present invention are the provlsion of a high speed actuator having rapid operational capabilities, the provision of a high speed actuator having simple and strong structural features which permit cleaner operation, less fouling, greater work life and efiicient operation; the provision of an actuator loaded 1n response to and reset by generated gases to provide high speed linear actuation and the provision of a high speed, gas Operated actuator suitable for use as a rapid fire mechanism for ballistic missile launchers and automatic weapons.

Further objects and advantages of the invention will become readily apparent as the following detailed description of the invention unfolds and when taken in conjunction with the drawings briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fully assembled side elevational view of the firing pin actuator illustrating the relative position of the parts during the firing of a projectile;

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FIG. 2 is a side view of the actuator of FIG. 1;

FIG. 3 illustrates the actuator of FIG. 1 in its retracted position after firing (shown in locked position);

FIG. 4 is a view of FIG. 1 illustrating the actuator 1n the rebound position as it fires a second projectile;

FIG. 5 is a partial sectional view of an embodiment of the actuator of the present invention;

FIG. 6 is a view partly in section of another embodiment of the firing pin actuator shown in the firing position; and,

FIG. 7 is a view of a dual chamber firing mechanism using the firing pin actuator of the present invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to a linear actuator adapted to provide high speed longitudinal movements in response to generated gases, The ensuing description will be described in terms of a firing pin mechanism adapted to provide high speed firing pin action for a ballistic launcher or automatic weapon. However, it will be appreciated that the invention is not restricted to such a firing pin but may be used in an unlimited number of sitnations where gas-operated high and low speed actuators are useful.

FIGS. 1-4 illustrate a preferred embodiment of the linear actuator of the present invention shown in its various stages of Operation. It will be appreciated that the dimensional changes shown in FIGS. 1, 3 and 4 in actual practice are minute as compared to the overall dimensions of the actuator mechanism. However, for the sake of clarity and to aid in the description these dimensions have been exaggerated in the drawings. The actuator consists of a rigid shaped vessel 10, which in its preferred embodiment is an ellipsoid turned on its longitudinal axis. A cylinder 12 is integrally attached to the front end of the vessel 10.

The cylinder 12, as shown more clearly in FIG. 2, includes a relatively fiat pressure responsive surface 14 and a cylindrical actuator pin 16 having an elliptically rounded tip which is the actual firing pin that strikes a projectile 18 mounted in a firing chamber 20.

The shape of the firing pin 16 is not critical and may be flat, conical, or elliptical depending upon the type of projectiles used. The actuator fits into a breech block chamber 22 in the breech block housing 24 so that the cylinder is slidably movable therein in response to the generation of gases within the firing chamber 20 by the detonation of a projectile or missile 18. A vent 26 in the firing chamber 20 may be provided to regulate the amount of gas which is forced through a firing pin passage 28 providing communication between the firing chamber and breech block chamber 22. A passage 30 is provided in the actuator cylinder 12, one end of which terminates at the pressure responsive surface 14 and the other end of which is in communication with the interior of the ellipsoid vessel 10. The interior end of the passage 30 is provided with a one-way valve 32 to permit gas flow into the ellipsoid vessel 10 from the chamber 22. A bleeder valve 34 is also provided at the rearward end of the ellipsoid 10 which is adjustable by any convenient means (not shown) so that the pressure build up within the vessel is controllable, which in turn controls the firing rate speed of the actuator.

The bleeder valve 34 will cause leakage of pressure from the vessel 10 when the pressure exceeds a predetermined value. It will be appreciated that the more gas that is vented, the longer it will take for pressure build-up within the vessel which will regulate the firing or forward motion of the firing pin 16 described hereinbelow.

A latch member 36 which would be preferably slidable within a slot 38 in the breech block housing 21, is integrally attached to the lower end of the cylinder 12. A second gear tooth member 40, operably connected to an exterior control means (not shown), preferably a shell or projectile feed means, is adapted to coact with the latch member 30 so when the shell feed means is nonoperative, the two latch members 36 and 40 abut each other and the actuator will remain in the loaded or compressed state, as shown in FIG. 3, until it is released again to fire.

In operation, when a gas producing device, such as a bullet, launcher, missile, or rocket is detonated, a force is created in the firing chamber 20 by the expansion of gases. Some or all of the expanding gases pass through the firing pin passage 28 and are applied to the pressure responsive surface 14 of the cylinder 12 depending on operational design requirements. This force compresses the ellipsoid in accordance with the following equation:

where P is expressed in p.s.i.g., the factor F is a function of the type of propellant used and is expressed in pounds per square inch per cubic centimeter per gram, W is the weight of the load expressed in grams and V is the total volume of the chamber 12 in cubic centimeter. Typical values for the force factor F (for common pressure-cartridge propellants) are:

Propellant: F p.s.i.g. cm. (gm.) Smokeless powder 127,000-142,000 Black powder 30,000-40,000 Pistol powder 127,000 Pyrocellulose 102,000 Composite (ammonium perchlorate) 133,000

The exhaust gases compress the ellipsoid vessel 1 in a direction indicated in FIG. 1, and at the same time, some of the gases enter the passage and pass through the oneway valve into the interior of the ellipsoid 10. FIG. 3 illustrates the distance AL that the shock wave pushes the actuator back from the firing position shown in FIG. 1.

The internal pressure created within the vessel may be approximated by the following equation assuming an isentropic expansion:

AL during an increment of time is represented by the following equation:

where V is the firing pin velocity at the beginning of the time increment t and E is the average acceleration during the time increment t.

An important design consideration is the third or rebound stage since the actuator is designed to produce a series of rapid compressions and rebounds of the ellipsoid, the materials involved must be considered with respect to flexibility, fatigue, wear and breakdown, which is a function of temperature during operation of the actuator. The average exhaust gas temperature by a perfect gas is approximated by the following equation:

where W is weight of propellant burned, 1 is the average 4 pressure p.s.i.g., V is volume in inches cubed of gases caught in the weapon, E is the average mass weight of the propellant and T is the average temperature.

The energy lost by the propellant gases during operation is equal to the energy lost through heat transfer through the ellipsoid walls, the kinetic energy of the accelerated mass, that is, work done in moving the ellipsoid a distance AL, the energy dissipated in overcoming friction, the kinetic energy of the propellant gases, and the potential energy of the compressed mass of the ellipsoid. This is approximated by the following equation:

where C is the average constant volume of specific heat of the propellant gases, T is the flame temperature of the propellant, T is the actual temperature of the gases, Q is the energy lost to heat transfer, X is the distance the ellipsoid is compressed, and 0 is the angle of launch from the horizontal.

Solution of the design temperature for the gases shows little error introduced in assuming the kinetic energy of the gases is zero. Further assuming that friction force is a constant percentage of the force on the ellipsoid, a friction loss of 10% of the ellipsoid forces is representative. Heat losses are calculated from the thermodynamic principles. The ratio for friction and heat loss is usually obtained in empirically using velocity data and pressuretime curves.

FIG. 4 illustrates the rebounding or reset position of the actuator through the distance L to the firing position, so that the cycle is again repeated.

It will be appreciated that the cycle is continuous so long as projectiles are detonated or until the actuator is disengaged by means of the latch 36 and gear tooth mechanism 40 shown in FIG. 3. In this position, gases remain within the interior of the ellipsoid vessel so that upon release of the latching means, the ellipsoid will reassume its natural shape shown in FIG. 1 and detonate a shell within the firing chamber.

FIG. 5 illustrates another embodiment of the ellipsoid vessel 101 wherein its interior chamber includes a honeycomb structure 102 forming a number of individual interconnected pressure chambers 104 and controlling pressure chamber 106. By regulating the number configuration, shape and design of the smaller pressure chambers 104, the time it takes to build up pressure within the larger chamber 106 may be varied to control the firing rate of the actuator while still maintaining the ellipsoid shape of the vessel 101.

For example a larger pressure chamber 104 with a smaller interconnection opening will take longer to fill than a small chamber with a large interconnection opening. Since these chambers are in a series configuration, the filling of the complete vessel 101 will depend upon the time it takes to fill the smaller chambers which in turn will regulate the firing rate of the actuator.

As indicated above, the shape of the vessel 10 is not critical. For example, the shape may be spherical, parabolic, or any other appropriately designed geometrical shape. FIG. 6 illustrates an actuator having a toroidal vessel 210' which is attached to a cylindrical element 212 having a cylindrically shaped end carrying a pin 214. A passage 216 permits gas to enter a chamber 216 through a one-way valve 218 to operate the actuator in a manner similar to the ellipsoid vessel as described above. Two- -'way valves 220 permit the pressurized gas to communicate with the interior of the toroidal vessel 210. Vents 222 are provided in the housing 224 to provide a means for the gas to escape to atmosphere. It should also be noted that in addition to the basic pressure vessel shape being a variable; the flexation of the chamber embodied with the ellipsoid can be changed to a rigid pressure vessel with movement of the firing pin geometry to create the pressure recoil by physical displacement.

FIG. 7 illustrates a dual firing chamber arrangement using the actuators of the present invention. Two ellipsoid vessels 310 and 312 are mounted within a breech block housing 314 in a side by side relationship. In the drawing, the upper actuator is shown in the loaded position while the lower actuator is shown in the firing position. The system operates in a manner similar to the actuator described above with respect to FIGS. 1 to 4 except that generated gases from one firing chamber are used to operate the opposite actuator. This is accomplished by two criss-cross passages 316 and 318 between one firing chamber to the interior of a second vessel. The passage need not communicate with the pressure responsive surfaces of the actuators but preferably would communicate with each vessel 310 at a position where movement is minimal as the vessel expands 'and contracts. Furthermore, a flexible coupling (not shown) at the point the passages 316 and 318 enter the vessels would insure the same amount of gas in the vessel interior during each cycle. This arrangement allows a filter 320 to be placed in each of the passages 316 and 318 to further eliminate fouling caused by impurities in the gas. This particular embodiment is shown as illustratory of a multiple series of actuators fired either singly, alternatively, multiply as the conditions are met.

It will be appreciated that the above described actuator may be used with conventional apparatus to facilitate cleaning, replacement and so forth. For example, a hinged cover may be provided in the breech block housing to permit removal of the actuator. Since no physical connections are required in the breech block housing, relacement is a simple matter.

As indicated above, while the invention described above is described with respect to a firing pin mechanism, it is not so limited. For example, it may have other applications such as riveting machines, hammers, and spot welders similar to the pneumatic type, where an internal or external supply of gas might be available. Various types of impacters, such as those used in dental work, could use the actuator described herein.

I claim:

1. A firing mechanism for high speed detonation of gas generating projectiles comprising, a housing, a pressure responsive vessel a portion of which is formed of flexible material, said vessel including a direct pressure responsive surface integral with said vessel and movable in response to gas pressure in said housing causing a rearward flexul'e of said vessel, a firing pin attached to and movable with said pressure responsive surface, an inner chamber and an opening permitting generated gases in said housing to enter said chamber causing expansion therein and a forward fiexure of said vessel, whereby harmonic motion is imparted to said vessel by the initial force of the generated gases against said pressure responsive surface to move said firing pin to a rearward cocked position and by the build of pressure within said vessel to cause a forward motion of said firing pin to the firing position.

2. The actuator of claim 1 wherein said pressure responsive vessel comprises a toroid.

3. The firing mechanism of claim 1 wherein said pressure responsive vessel is an ellipsoid.

4. The firing mechanism of claim 1 further including means to maintain said firing pin in a cocked position.

5. The firing mechanism of claim 1 including means to regulate the rate of fire of said firing pin during multiple firing conditions.

References Cited UNITED STATES PATENTS 515,064 2/1904 Unge 89-192X 908,294 12/1908 Marga 89-191X 1,856,022 4/ 1932 Blacker. 2,756,639 7/1956 Bird 89-159X 2,895,383 7/1959 Reed 89-491 3,311,022 3/1967 Bernard et al. 89-159X FOREIGN PATENTS 147,371 7/ 1920 Great Britain 89-192 BENJAMIN A. BORCHELT, Primary Examiner S. C. BENTLEY, Assistant Examiner U.S. Cl. X.R. 89127, 193 

